Study on the Frost Resistance of Concrete Modified with Steel Balls Containing Phase Change Material (PCM)

In order to investigate the effect of phase change materials on the frost resistance of concrete in cold regions, hollow steel balls were used in this paper for the macroscopic encapsulation of the phase change material to replace some of the coarse aggregates in the preparation of phase change concrete. On the premise of ensuring reasonable mechanical properties, concrete mixed with different contents and different surface treatments of grouting steel balls were tested for the compressive strength and splitting tensile strength to determine the optimum content of phase change steel balls and investigate the frost resistance of phase change concrete. At the same time, industrial CT was used to explore the internal pore evolution pattern of concrete during the freeze-thaw period. The test results show that the optimum content of steel balls is 75%; during the freeze-thaw process, the mass loss, relative dynamic elastic modulus loss, and strength loss of phase change concrete are all lower than those of ordinary concrete, and the increase in porosity of phase change concrete is also significantly lower than that of ordinary concrete; the addition of phase change materials can optimise the distribution of the internal pore in concrete, improve its internal pore structure, and enhance its frost resistance.